Mr Trump said the 2015 nuclear deal negotiated by his predecessor, Barack Obama, was "an embarrassment" and hinted that he may not recertify the agreement when it comes up for a mid-October deadline. He said: "I don't think you've heard the last of it.” The Iran nuclear deal was forged two years ago following extensive talks between the gulf nation Iran and world powers - the US, UK, France, China, Russia and Germany. Tough economic sanctions which had strangled the country were lifted in return for Iran radically reducing its nuclear facilities, which it had always claimed were for energy purposes and not for weapons manufacturing.  But Mr Trump called Iran an "economically depleted rogue state" that exports violence. He has already promised to withdraw the US from the historic Paris climate accord, and his latest comments suggest he is ready to reverse yet another piece of Obama-era diplomacy. Tehran has yet to comment on Mr Trump's speech. In an extraordinary speech to the international peace-keeping organisation, the US Commander-in-Chief also said he would be forced to "totally destroy" North Korea if the rogue nation continued to develop nuclear weapons and threaten America. He mocked North Korean leader Kim Jong-un, labelling him "rocket man" for his continued missile launches and nuclear tests in breach of UN orders. Mr Trump told the UN General Assembly in New York: "We will have no choice than to totally destroy North Korea. "Rocket man is on a suicide mission for himself and his regime." North Korea's mission to the United Nations did not immediately respond to a request for comment on the US President's remarks. A junior North Korean diplomat remained in the delegation's front-row seat for Trump's speech, the North Korean UN mission said. Minutes before he took the floor, UN Secretary-General Antonio Guterres had appealed for statesmanship. But instead Mr Trump did what he did best - unleash a volley of incendiary attacks on other nations while hammering home his "America First" message. Although he stuck closely to his script, there was plenty in his speech to leave seasoned diplomats used to more measured rhetoric from world leaders exasperated. The President's verbal attack on Pyongyang drew mumbles from the UN General Assembly Hall, Reuters reported. One man in the audience covered his face with his hands shortly after Trump made his "totally destroy" comment. Swedish Foreign Minister Margot Wallstrom crossed her arms. Once again, the President's words also went against many of his most senior White House officials, who have repeatedly called for the North Korean crisis to be solved through diplomatic means.